
public class helloWorld {
    public static void main(String[] args) {
        // System.out.print("hello world");
        System.out.println("abcd".length());
        System.out.println("abcd".substring(3, 4));
        System.out.println("abcd".substring(3));
        char[] chars = "abcd".toCharArray();
        System.out.println(String.copyValueOf(chars, 0, 1));
    }
}